This invention relates to an improved method for the production of dry or semi-dry sausages by the addition of the bacterial concentrate Pediococcus pentosaceus, ATCC 10791. Through this invention the fermentation can be controlled to such a degree that the time required to obtain a desirable product is significantly reduced.
Dry and semi-dry sausage can generally be distinguished from other meat products in that they require a fermentation step. Historically, the processing of a meat emulsion into a sausage product by fermentation has been more an art than a science. In the traditional method of sausage manufacture, the meat mixture is first pan cured for two to three days after which it is stuffed and held in a "green room" or fermentation chamber to begin its fermentation cycle. During this fermentation cycle lactic acid is produced which in turn lowers the pH and imparts desirable flavor characteristics to the meat. In the case of dry sausage, the fermentation cycle is followed by a finishing or drying cycle wherein the sausage is dried to some minimal moisture content. Once it is processed the dry sausage can be stored for long periods of time without refrigeration. Examples of dry sausages include pepperoni, genoa salami, hard salami, San Francisco Italian style salami and others. The semi-dry sausage, which is only partially dried to some desirable moisture content, must be refrigerated to prevent the growth of microorganisms which may spoil the meat.
The fermentation step to which this invention is directed effectuates a conversion of the sugars present in a meat formulation to lactic acid. The presence of lactic acid reduces the pH of the meat emulsion thereby speeding up the curing process. As the pH of the sausage is lowered due to an increase in the amount of lactic acid, other products are formed which enhance the flavor of the sausage. To initiate the fermentation process the sausage is stuffed and held in a fermentation chamber at some suitable fermentation temperature.
Basically, two methods have been used to control the fermentation cycle in the processing of sausage. A first method involves maintaining the sausage internal temperature between 75.degree. F. and 80.degree. F. wherein the maximum temperature is achieved during the fermentation cycle. After a desired degree of fermentation has been reached, the sausage is placed in a drying cycle. The total time required to process sausage by this method is long, namely, about 18 days to 6 weeks.
A second method of processing the sausage is to maintain the sausage internal temperature during fermentation at some higher value in the range of 95.degree. F. to 115.degree. F. This fermentation cycle may then be followed by a drying step at 110.degree. F. to 160.degree. F. While the processing cycle for this method is shorter than that wherein the fermentation is carried out at a lower temperature, there are other disadvantages inherent to this method.
Initiation of the fermentation can be accomplished in a number of different ways. In the past the sausage manufacturer would rely on chance inoculation whereby advantage was taken of the natural bacteria or microorganisms present in the meat emulsion. These microorganisms would then ferment the nutrients in the meat to lactic acid. Another previously used method consisted of inoculating the meat with sausage from a prior batch (called "back slopping"). By this method the microorganisms present in the fermented sausage could be utilized to initiate fermentation of the meat emulsion.
Neither of these known methods offered the sausage manufacturer a reliable way to control the fermentation. Subsequently, commercial starter cultures consisting of certain microorganisms were developed. These cultures consisted of lactic acid producing microorganisms which when added to a meat emulsion under specified operating conditions, would convert the nutrients present in the meat formulation into lactic acid. A number of bacteria for use as starter cultures have been disclosed in the prior art. A commonly used starter culture for the fermentation of a meat emulsion to produce sausage is one consisting of Pediococcus cerevisiae, also known as Pediococcus acidilactici. Later developments in the art involved the use of different bacteria in an attempt to control the fermentation more effectively. On such bacteria was the Lactobacillus plantarum NRRL-B-5461.
In all of the processes used prior to the availability of starter cultures there was difficulty in obtaining consistent and uniform sausage. Also, the required processing times were lengthy. The use of starter cultures such as Pediococcus cerevisiae made it possible for sausage manufacturers to improve control of the fermentation cycle and to obtain a more uniform sausage. None of the starter cultures previously used have been able to satisfy all of the needs of the sausage manufacturer.
A need exists for a finished sausage product which has a desirable or traditional flavor, color and texture and which can be produced as quickly as possible. To obtain the desired flavor the pH in the sausage must be accurately controlled. When fermenting at low temperatures, i.e., below 80.degree. F., the previously used cultures become less effective and as a result do not allow for acceptable pH control. This lack of pH control renders it impossible to achieve the desired flavor.
Similarly, if fermentation is conducted at higher temperatures above 80.degree. F., the processing can be completed in a shorter time but the flavor characteristics are altered due to the higher temperature. In addition, while the commercially available cultures increase the speed of the fermentation cycle, operating at higher temperatures significantly increases the risk of stimulating the growth of putrefying or contaminating bacteria such as Staphylococcus aureus. Since the Staphylococcus strain is aerobic and grows in the outer ring of the stuffed sausage, the cultured used to ferment the sausage has little inhibitory effect. Consequently, as the fermentation temperature is increased, a greater growth of pathogenic microorganisms is realized.
There are additional processing problems when operating at higher temperatures including fat rendering and overall handling of the product.